1. Field of the Invention
The present invention relates to a method for recovery of phosphate from a liquid phase, wherein a magnesium electrode and a further electrode are interconnected to form a first electrolysis cell, with the interposition of the liquid phase as an electrolyte solution.
2. Description of the Related Art
Such a method is already previously known from US 2014/0021057 A1. The object of this document is a method for the treatment of wastewater, within the scope of which phosphates are to be extracted from the wastewater in order to purify them for further use.
Due to fertilizer application using phosphates and nitrogen compounds, these substances get into wastewater, which is then drained into the sewer system along with rain. From there, they are conducted to sewage treatment plants, in which treatment of the water for further use is carried out. For this purpose, the aforementioned method provides for binding orthophosphates and ammonium, using an electrolysis cell, in an electrolytic method, in that magnesium is supplied by way of a sacrificial anode. In this connection, within the scope of the electrolysis method, magnesium ammonium phosphate, called struvite, which can be used as a fertilizer, is formed. It can be precipitated from the liquid phase and extracted from it.
Industrial wastewater, with the focus here being particularly on wastewater from hydrothermal carbonization, does not necessarily contain ammonium, so that an addition of ammonium would be necessary to carry out the method described above; this would be cost-intensive and ineffective. Therefore, as an alternative to the method mentioned above, a possibility is being sought for extracting only phosphates, for example orthophosphates, from a liquid phase, without the addition of cost-intensive and simultaneously environmentally harmful substances being required for this purpose. Furthermore, it represents an additional work step that the bound phosphate is once again filtered out of the electrolyte solution.